The Abbreviated History of the
Periodic Table for Regents Chemistry
1829-Geman Chemist Johann Dobereiner (Dobereiner
PDF article by Dr. James L. Marshall) started the
challenge of constructing a Periodic Table. About 60
elements were known at this time. He grouped elements based
on similarities. He then proposed the Law of Triads:
Middle element in the triad had atomic weight that was the
average of the other two members.
Ca(40) Sr(88) and Ba (137) Hey (137 +
40)/2= 88
Dobereiner noticed the same pattern for the
alkali metal triad (group 1 now) and the halogen
triad (group 17).
(I) lithium,
sodium and potassium
(II) calcium,
strontium and barium
(XVII) chlorine,
bromine and iodine
1862-Alexandre Beguyer de Chancourtois professor at the
School of Mines in Paris. he Published a list of known
elements. this list was constructed as a continuous graph
wrapped around in a cylinder, where elements that
exhibited similar properties occupied the same column. He
didn't have any pretty pictures to go with his work, so it
went ignored until Dmitri
Mendeleev come along.
1864 – English chemist John Newlands – early table likened
periodicity to the musical octave – “law of octaves”
– properties repeated with every eighth element.
1869-The
Russian scientist Dmitri Mendeleev first organized the elements into a table based upon properties of the
elements that were recurrent (periodic).Elements in the same column (Group) generally have similar properties.
